dhi: update get started (#24228)

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## Description

Updated get-started to inform enterprise/trial users at the start of the
topic that they must mirror and pull from Hub instead of dhi.io.

This is a band-aid to a bigger gap, "Get started with DHI Enterprise",
that will need to be addressed.

## Related issues or tickets

ENGDOCS-3208

## Reviews

<!-- Notes for reviewers here -->
<!-- List applicable reviews (optionally @tag reviewers) -->

- [ ] Editorial review

---------

Signed-off-by: Craig Osterhout <craig.osterhout@docker.com>

Author: craig-osterhout

content/manuals/dhi/get-started.md

@@ -11,12 +11,16 @@ This guide shows you how to go from zero to running a Docker Hardened Image
 Docker image to better understand the differences. While the steps use a
 specific image as an example, they can be applied to any DHI.
 
-> [!NOTE]
->
-> Docker Hardened Images are freely available to everyone with no subscription
-> required, no usage restrictions, and no vendor lock-in. You can upgrade to a
-> DHI Enterprise subscription when you require enterprise features like FIPS or
-> STIG compliance variants, customization capabilities, or SLA-backed support.
+Docker Hardened Images are freely available to everyone with no subscription
+required, no usage restrictions, and no vendor lock-in. This quickstart covers
+free DHI images pulled from `dhi.io`. If you have a DHI Enterprise subscription
+or have started a trial and need compliance variants (FIPS), customization
+capabilities, or SLA-backed updates, you must [mirror DHI
+repositories](./how-to/mirror.md) to your organization's namespace on Docker
+Hub. You then pull mirrored images from `docker.io` (not `dhi.io`) using your
+organization's namespace path. For example, `docker pull
+docker.io/<yourorg>/dhi-python:3.13` instead of `docker pull
+dhi.io/python:3.13`.
 
 ## Step 1: Find an image to use